How to create ship painted metal panels material?
First, the initial results are good.
I would say don't connect the same thing to both normal sockets.  Do use the clearcoat normal (and I'm a fan of including whatever level of microdetail you want) but consider mixing in much larger scale imperfection as well, to try and coax this type of imperfect reflection from the clearcoat layer.

Make another bump node for the surface Normal socket.
Perhaps this type of wave texture:

And maybe add (clamped) some noise in for good measure: